Recently, there are many studies on synthetic wood having surface texture and patterns similar with natural timber. The synthetic wood has the external appearance or properties similar with natural timber because it contains lots of wood flour, and is manufactured through injection molding or extrusion molding.
A plastic material used for the injection molding or the extrusion molding is mainly polyolefin, such as polyethylene (PE) and polypropylene (PP), because polyolefin which is nontoxic is suitable for synthetic wood carrying the banner for eco-friendly material, and is manufactured through injection molding or extrusion molding. Because the injection-molded product is engraved or has the grain of wood at the time of molding, it can express the texture of wood without the secondary process such as printing or painting.
The extrusion-molded product is similar to material, slab, or lumber of wood, and is mainly used for building materials.
Synthetic wood is generally lower in absorptiveness than natural timber and is uncorrupted. Moreover, the synthetic wood is very high in intensity and is favorable for processing such as nailing or planning because it is relatively lower in foaming magnitude and has an outer layer with high density.
Because the synthetic wood has strong and excellent physical properties and is eco-friendly and renewable, it has been seeing rapid growth in its market as a new material replacing natural wood, and synthetic wood products of various forms have been developed.
In the meantime, most of conventional synthetic woods are manufactured by a method of expressing patterns through a mechanical postprocess, and are sometimes manufactured by a method of expressing patterns using pigments.
However, most of the conventional extrusion-molded synthetic wood products have a problem in that they cannot realize actual patterns, such as waves, lines, oblique lines, dotted lines, of the real high-quality wood because they have solid color and monotonous patterns.
Accordingly, in order to express some pattern, a wooden pattern master batch is put in the middle of an extruder, but it is difficult to realize the natural pattern of real wood.